In vivo, PDE4 inhibitors demonstrated bronchodilatory effects and the ability to reverse bronchospasm induced by a variety of agents, thus, the profile of selective PDE4 inhibitors appeared to fulfil the requirement for the treatment of inflammation-based pathologies such as asthma and chronic obstructive pulmonary disease (COPD) and some auto-immune diseases [15,59,60,61,62]. Here, PDE4A is linked to chronic obstructive pulmonary disease.